Estiquote

Local costs · East of England · September 2026

How much does an extension cost in Colchester?

A mid-range 25 m² single-storey extension in Colchester costs about £67,500 to £83,500 including VAT, or £2,700 to £3,300 per m² at East of England prices. Colchester charges £925 for building control on a 10 to 40 m² extension (full plans, VAT status not stated): 10% above the typical council (£840). With design, a structural engineer, building control and a 15% contingency, budget £83,500 to £108,000.

By Estiquote · Prices reviewed · Council fees from Colchester's published schedule · How we calculate

Work out your project in Colchester

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Typical prices in Colchester

Mid-range finish, East of England prices, including VAT. The budget adds design and engineering fees, Colchester's building control charge and a 15% contingency.
ProjectBuilding workBudget to plan for
Single-storey extension, 25 m²£67,500 to £83,500£83,500 to £108,000
Double-storey extension, 40 m²£97,500 to £123,000£120,000 to £156,000
Dormer loft conversion, 30 m²£60,500 to £74,500£75,000 to £95,500
Kitchen, medium£9,300 to £16,600£10,700 to £19,000
Bathroom refit£6,300 to £9,400£7,200 to £10,800

Building prices in East of England run about 7% above the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.

Building control fees in Colchester

Colchester council charges including VAT (plan and inspection combined)
WorkCharge
Extension up to 10 m² (full plans)£565
Extension 10 to 40 m² (full plans)£925
Larger extension, 40-100 m² (full plans)£1,155
Extension 10 to 40 m² (building notice)£925
Loft conversion up to 40 m²£1,075
Garage conversion£650

Colchester charges £925 for building control on a 10 to 40 m² extension (full plans, VAT status not stated): 10% above the typical council (£840). Source: Colchester's building control charges, Not stated on page text (page indexed as "New Building Regulation application charges from 1 April 2026"). Inspection and building-notice totals shown inc VAT; VAT status of GBP275 plan check fee not stated.

Check before relying on it: the schedule does not say whether VAT is included.

Private approved inspectors set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Colchester compares with every council we checked.

Notes on Colchester's schedule

Own page. Full plans = plan check fee GBP275 (alterations) + inspection total; this equals the published building-notice total.

Planning

If your extension needs planning permission, a householder application in England costs £548. Many single-storey rear extensions are permitted development and need no application, and a lawful development certificate (£274) confirms it.

Other councils in East of England

Building control for a 10 to 40 m² extension:

Questions people ask

How much does an extension cost in Colchester?

A mid-range 25 m² single-storey extension in Colchester costs about £67,500 to £83,500 including VAT for the building work, or £2,700 to £3,300 per m², based on East of England prices reviewed in September 2026. With fees and a 15% contingency, budget £83,500 to £108,000.

How much is building control in Colchester?

Colchester charges £925 (VAT status not stated) for a 10 to 40 m² extension (full plans), according to its published schedule (Not stated on page text (page indexed as "New Building Regulation application charges from 1 April 2026")).

How much does a loft conversion cost in Colchester?

A mid-range 30 m² dormer loft conversion in Colchester costs about £60,500 to £74,500 including VAT for the building work, and about £75,000 to £95,500 with fees and a 15% contingency.

Before you get quotes